1. Field of the Invention
The present invention relates to safety shutoff apparatus that is able to protect against leaks.
2. Description of Related Art
Appliances such as water heaters, clothes washing machines and the like can spontaneously leak. Leaks can also come from worn or defective valves or from pipes or other plumbing fixtures that burst when frozen. If the owner is absent the leak can cause flooding and substantial damage.
Various emergency shutoff valves have been proposed that employ a water sensor that operates another device that is capable of closing a valve. The drawback with these designs is that the sensors or the shutoff device is relatively complicated and may require an external source of power such as electricity. Also, these devices are not easily adapted to monitoring leaks at remote locations or multiple locations.
In the housing 22 of U.S. Pat. No. 3,920,031 spring biased plunger 26 presses against a plug 30 made of “sugar, salt, or the like.” Column 3, lines 20-21. A leak from the water heater can dissolve the plug and pull wire 36 to release catch 68 from the notch 64, so that the valve is shut off by means of coil spring 58.
In U.S. Pat. No. 6,024,116 a valve stem 36 is held in place by flexible fingers 106 that press into grooves 104 and are held in place by a reinforcing paper collar 38. Paper collar 38 is water-soluble and leakage from a hot water heater will soften collar 38 to the point where it will deform or tear and thereby release valve stem 36, thereby closing the valve.
In U.S. Pat. No. 4,877,049 the timer on a washing machine starts an air compressor 16/17 to open hydraulically operated valves 5. Water from a leak lifts float 20 to open electrical contacts 19 and stop air compressor 16/17, thereby closing valves 5. See also U.S. Pat. No. 4,141,533 (solenoid valve actuated to supply pressure to a cylinder that closes a valve).
In U.S. Pat. No. 6,206,337 a retrofit device is clamped to a water supply pipe to operate a shut off valve. A sensor can electrically operate solenoid 35 to release a catch 40 so that spring 32 can swing handle 15 and close valve 60.
In U.S. Pat. No. 5,771,916 leaking water enters a containment chamber of a shut off valve and causes block 82 to expand in order to swing lever 84 and release arm 70 so that spring 78 can close the valve.
In U.S. Pat. No. 6,253,785 float 40 lifts hook 34 to release valve handle 32 so that spring 28 can close shut off valve 24.
In U.S. Pat. No. 4,437,482 a water soluble band 24 that wraps around fingers 26 and 28 can dissolve and release spring-loaded shuttle 18 to close port 20 and prevent water intrusion that may otherwise damage a gas leak detector.
In FIG. 7 of U.S. Patent Application Publication No. U.S. 2002/0074042 a valve designed to close in response to high water flow rates is initially kept open after installation by a water-soluble plug 300.
See also U.S. Pat. No. 5,253,619 (electrically controlled hydraulic actuator operates an engine valve).
Accordingly, there is a need for an improved safety shutoff apparatus that is able to simply and reliably protect against leaks.